Import LLVM 10.0.0 release including clang, lld and lldb.

ok hackroom
tested by plenty

1 files changed, 956 insertions, 0 deletions

diff --git a/gnu/llvm/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp b/gnu/llvm/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
new file mode 100644
index 00000000000..029bfe1cd60
--- /dev/null
+++ b/gnu/llvm/clang/lib/Lex/DependencyDirectivesSourceMinimizer.cpp
@@ -0,0 +1,956 @@
+//===- DependencyDirectivesSourceMinimizer.cpp -  -------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This is the implementation for minimizing header and source files to the
+/// minimum necessary preprocessor directives for evaluating includes. It
+/// reduces the source down to #define, #include, #import, @import, and any
+/// conditional preprocessor logic that contains one of those.
+///
+//===----------------------------------------------------------------------===//
+
+#include "clang/Lex/DependencyDirectivesSourceMinimizer.h"
+#include "clang/Basic/CharInfo.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Lex/LexDiagnostic.h"
+#include "llvm/ADT/StringSwitch.h"
+#include "llvm/Support/MemoryBuffer.h"
+
+using namespace llvm;
+using namespace clang;
+using namespace clang::minimize_source_to_dependency_directives;
+
+namespace {
+
+struct Minimizer {
+  /// Minimized output.
+  SmallVectorImpl<char> &Out;
+  /// The known tokens encountered during the minimization.
+  SmallVectorImpl<Token> &Tokens;
+
+  Minimizer(SmallVectorImpl<char> &Out, SmallVectorImpl<Token> &Tokens,
+            StringRef Input, DiagnosticsEngine *Diags,
+            SourceLocation InputSourceLoc)
+      : Out(Out), Tokens(Tokens), Input(Input), Diags(Diags),
+        InputSourceLoc(InputSourceLoc) {}
+
+  /// Lex the provided source and emit the minimized output.
+  ///
+  /// \returns True on error.
+  bool minimize();
+
+private:
+  struct IdInfo {
+    const char *Last;
+    StringRef Name;
+  };
+
+  /// Lex an identifier.
+  ///
+  /// \pre First points at a valid identifier head.
+  LLVM_NODISCARD IdInfo lexIdentifier(const char *First, const char *const End);
+  LLVM_NODISCARD bool isNextIdentifier(StringRef Id, const char *&First,
+                                       const char *const End);
+  LLVM_NODISCARD bool minimizeImpl(const char *First, const char *const End);
+  LLVM_NODISCARD bool lexPPLine(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexAt(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexModule(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexDefine(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexPragma(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexEndif(const char *&First, const char *const End);
+  LLVM_NODISCARD bool lexDefault(TokenKind Kind, StringRef Directive,
+                                 const char *&First, const char *const End);
+  Token &makeToken(TokenKind K) {
+    Tokens.emplace_back(K, Out.size());
+    return Tokens.back();
+  }
+  void popToken() {
+    Out.resize(Tokens.back().Offset);
+    Tokens.pop_back();
+  }
+  TokenKind top() const { return Tokens.empty() ? pp_none : Tokens.back().K; }
+
+  Minimizer &put(char Byte) {
+    Out.push_back(Byte);
+    return *this;
+  }
+  Minimizer &append(StringRef S) { return append(S.begin(), S.end()); }
+  Minimizer &append(const char *First, const char *Last) {
+    Out.append(First, Last);
+    return *this;
+  }
+
+  void printToNewline(const char *&First, const char *const End);
+  void printAdjacentModuleNameParts(const char *&First, const char *const End);
+  LLVM_NODISCARD bool printAtImportBody(const char *&First,
+                                        const char *const End);
+  void printDirectiveBody(const char *&First, const char *const End);
+  void printAdjacentMacroArgs(const char *&First, const char *const End);
+  LLVM_NODISCARD bool printMacroArgs(const char *&First, const char *const End);
+
+  /// Reports a diagnostic if the diagnostic engine is provided. Always returns
+  /// true at the end.
+  bool reportError(const char *CurPtr, unsigned Err);
+
+  StringMap<char> SplitIds;
+  StringRef Input;
+  DiagnosticsEngine *Diags;
+  SourceLocation InputSourceLoc;
+};
+
+} // end anonymous namespace
+
+bool Minimizer::reportError(const char *CurPtr, unsigned Err) {
+  if (!Diags)
+    return true;
+  assert(CurPtr >= Input.data() && "invalid buffer ptr");
+  Diags->Report(InputSourceLoc.getLocWithOffset(CurPtr - Input.data()), Err);
+  return true;
+}
+
+static void skipOverSpaces(const char *&First, const char *const End) {
+  while (First != End && isHorizontalWhitespace(*First))
+    ++First;
+}
+
+LLVM_NODISCARD static bool isRawStringLiteral(const char *First,
+                                              const char *Current) {
+  assert(First <= Current);
+
+  // Check if we can even back up.
+  if (*Current != '"' || First == Current)
+    return false;
+
+  // Check for an "R".
+  --Current;
+  if (*Current != 'R')
+    return false;
+  if (First == Current || !isIdentifierBody(*--Current))
+    return true;
+
+  // Check for a prefix of "u", "U", or "L".
+  if (*Current == 'u' || *Current == 'U' || *Current == 'L')
+    return First == Current || !isIdentifierBody(*--Current);
+
+  // Check for a prefix of "u8".
+  if (*Current != '8' || First == Current || *Current-- != 'u')
+    return false;
+  return First == Current || !isIdentifierBody(*--Current);
+}
+
+static void skipRawString(const char *&First, const char *const End) {
+  assert(First[0] == '"');
+  assert(First[-1] == 'R');
+
+  const char *Last = ++First;
+  while (Last != End && *Last != '(')
+    ++Last;
+  if (Last == End) {
+    First = Last; // Hit the end... just give up.
+    return;
+  }
+
+  StringRef Terminator(First, Last - First);
+  for (;;) {
+    // Move First to just past the next ")".
+    First = Last;
+    while (First != End && *First != ')')
+      ++First;
+    if (First == End)
+      return;
+    ++First;
+
+    // Look ahead for the terminator sequence.
+    Last = First;
+    while (Last != End && size_t(Last - First) < Terminator.size() &&
+           Terminator[Last - First] == *Last)
+      ++Last;
+
+    // Check if we hit it (or the end of the file).
+    if (Last == End) {
+      First = Last;
+      return;
+    }
+    if (size_t(Last - First) < Terminator.size())
+      continue;
+    if (*Last != '"')
+      continue;
+    First = Last + 1;
+    return;
+  }
+}
+
+// Returns the length of EOL, either 0 (no end-of-line), 1 (\n) or 2 (\r\n)
+static unsigned isEOL(const char *First, const char *const End) {
+  if (First == End)
+    return 0;
+  if (End - First > 1 && isVerticalWhitespace(First[0]) &&
+      isVerticalWhitespace(First[1]) && First[0] != First[1])
+    return 2;
+  return !!isVerticalWhitespace(First[0]);
+}
+
+static void skipString(const char *&First, const char *const End) {
+  assert(*First == '\'' || *First == '"' || *First == '<');
+  const char Terminator = *First == '<' ? '>' : *First;
+  for (++First; First != End && *First != Terminator; ++First) {
+    // String and character literals don't extend past the end of the line.
+    if (isVerticalWhitespace(*First))
+      return;
+    if (*First != '\\')
+      continue;
+    // Skip past backslash to the next character. This ensures that the
+    // character right after it is skipped as well, which matters if it's
+    // the terminator.
+    if (++First == End)
+      return;
+    if (!isWhitespace(*First))
+      continue;
+    // Whitespace after the backslash might indicate a line continuation.
+    const char *FirstAfterBackslashPastSpace = First;
+    skipOverSpaces(FirstAfterBackslashPastSpace, End);
+    if (unsigned NLSize = isEOL(FirstAfterBackslashPastSpace, End)) {
+      // Advance the character pointer to the next line for the next
+      // iteration.
+      First = FirstAfterBackslashPastSpace + NLSize - 1;
+    }
+  }
+  if (First != End)
+    ++First; // Finish off the string.
+}
+
+// Returns the length of the skipped newline
+static unsigned skipNewline(const char *&First, const char *End) {
+  if (First == End)
+    return 0;
+  assert(isVerticalWhitespace(*First));
+  unsigned Len = isEOL(First, End);
+  assert(Len && "expected newline");
+  First += Len;
+  return Len;
+}
+
+static bool wasLineContinuation(const char *First, unsigned EOLLen) {
+  return *(First - (int)EOLLen - 1) == '\\';
+}
+
+static void skipToNewlineRaw(const char *&First, const char *const End) {
+  for (;;) {
+    if (First == End)
+      return;
+
+    unsigned Len = isEOL(First, End);
+    if (Len)
+      return;
+
+    do {
+      if (++First == End)
+        return;
+      Len = isEOL(First, End);
+    } while (!Len);
+
+    if (First[-1] != '\\')
+      return;
+
+    First += Len;
+    // Keep skipping lines...
+  }
+}
+
+static const char *findLastNonSpace(const char *First, const char *Last) {
+  assert(First <= Last);
+  while (First != Last && isHorizontalWhitespace(Last[-1]))
+    --Last;
+  return Last;
+}
+
+static const char *findFirstTrailingSpace(const char *First,
+                                          const char *Last) {
+  const char *LastNonSpace = findLastNonSpace(First, Last);
+  if (Last == LastNonSpace)
+    return Last;
+  assert(isHorizontalWhitespace(LastNonSpace[0]));
+  return LastNonSpace + 1;
+}
+
+static void skipLineComment(const char *&First, const char *const End) {
+  assert(First[0] == '/' && First[1] == '/');
+  First += 2;
+  skipToNewlineRaw(First, End);
+}
+
+static void skipBlockComment(const char *&First, const char *const End) {
+  assert(First[0] == '/' && First[1] == '*');
+  if (End - First < 4) {
+    First = End;
+    return;
+  }
+  for (First += 3; First != End; ++First)
+    if (First[-1] == '*' && First[0] == '/') {
+      ++First;
+      return;
+    }
+}
+
+/// \returns True if the current single quotation mark character is a C++ 14
+/// digit separator.
+static bool isQuoteCppDigitSeparator(const char *const Start,
+                                     const char *const Cur,
+                                     const char *const End) {
+  assert(*Cur == '\'' && "expected quotation character");
+  // skipLine called in places where we don't expect a valid number
+  // body before `start` on the same line, so always return false at the start.
+  if (Start == Cur)
+    return false;
+  // The previous character must be a valid PP number character.
+  // Make sure that the L, u, U, u8 prefixes don't get marked as a
+  // separator though.
+  char Prev = *(Cur - 1);
+  if (Prev == 'L' || Prev == 'U' || Prev == 'u')
+    return false;
+  if (Prev == '8' && (Cur - 1 != Start) && *(Cur - 2) == 'u')
+    return false;
+  if (!isPreprocessingNumberBody(Prev))
+    return false;
+  // The next character should be a valid identifier body character.
+  return (Cur + 1) < End && isIdentifierBody(*(Cur + 1));
+}
+
+static void skipLine(const char *&First, const char *const End) {
+  for (;;) {
+    assert(First <= End);
+    if (First == End)
+      return;
+
+    if (isVerticalWhitespace(*First)) {
+      skipNewline(First, End);
+      return;
+    }
+    const char *Start = First;
+    while (First != End && !isVerticalWhitespace(*First)) {
+      // Iterate over strings correctly to avoid comments and newlines.
+      if (*First == '"' ||
+          (*First == '\'' && !isQuoteCppDigitSeparator(Start, First, End))) {
+        if (isRawStringLiteral(Start, First))
+          skipRawString(First, End);
+        else
+          skipString(First, End);
+        continue;
+      }
+
+      // Iterate over comments correctly.
+      if (*First != '/' || End - First < 2) {
+        ++First;
+        continue;
+      }
+
+      if (First[1] == '/') {
+        // "//...".
+        skipLineComment(First, End);
+        continue;
+      }
+
+      if (First[1] != '*') {
+        ++First;
+        continue;
+      }
+
+      // "/*...*/".
+      skipBlockComment(First, End);
+    }
+    if (First == End)
+      return;
+
+    // Skip over the newline.
+    unsigned Len = skipNewline(First, End);
+    if (!wasLineContinuation(First, Len)) // Continue past line-continuations.
+      break;
+  }
+}
+
+static void skipDirective(StringRef Name, const char *&First,
+                          const char *const End) {
+  if (llvm::StringSwitch<bool>(Name)
+          .Case("warning", true)
+          .Case("error", true)
+          .Default(false))
+    // Do not process quotes or comments.
+    skipToNewlineRaw(First, End);
+  else
+    skipLine(First, End);
+}
+
+void Minimizer::printToNewline(const char *&First, const char *const End) {
+  while (First != End && !isVerticalWhitespace(*First)) {
+    const char *Last = First;
+    do {
+      // Iterate over strings correctly to avoid comments and newlines.
+      if (*Last == '"' || *Last == '\'' ||
+          (*Last == '<' && top() == pp_include)) {
+        if (LLVM_UNLIKELY(isRawStringLiteral(First, Last)))
+          skipRawString(Last, End);
+        else
+          skipString(Last, End);
+        continue;
+      }
+      if (*Last != '/' || End - Last < 2) {
+        ++Last;
+        continue; // Gather the rest up to print verbatim.
+      }
+
+      if (Last[1] != '/' && Last[1] != '*') {
+        ++Last;
+        continue;
+      }
+
+      // Deal with "//..." and "/*...*/".
+      append(First, findFirstTrailingSpace(First, Last));
+      First = Last;
+
+      if (Last[1] == '/') {
+        skipLineComment(First, End);
+        return;
+      }
+
+      put(' ');
+      skipBlockComment(First, End);
+      skipOverSpaces(First, End);
+      Last = First;
+    } while (Last != End && !isVerticalWhitespace(*Last));
+
+    // Print out the string.
+    const char *LastBeforeTrailingSpace = findLastNonSpace(First, Last);
+    if (Last == End || LastBeforeTrailingSpace == First ||
+        LastBeforeTrailingSpace[-1] != '\\') {
+      append(First, LastBeforeTrailingSpace);
+      First = Last;
+      skipNewline(First, End);
+      return;
+    }
+
+    // Print up to the backslash, backing up over spaces. Preserve at least one
+    // space, as the space matters when tokens are separated by a line
+    // continuation.
+    append(First, findFirstTrailingSpace(
+                      First, LastBeforeTrailingSpace - 1));
+
+    First = Last;
+    skipNewline(First, End);
+    skipOverSpaces(First, End);
+  }
+}
+
+static void skipWhitespace(const char *&First, const char *const End) {
+  for (;;) {
+    assert(First <= End);
+    skipOverSpaces(First, End);
+
+    if (End - First < 2)
+      return;
+
+    if (First[0] == '\\' && isVerticalWhitespace(First[1])) {
+      skipNewline(++First, End);
+      continue;
+    }
+
+    // Check for a non-comment character.
+    if (First[0] != '/')
+      return;
+
+    // "// ...".
+    if (First[1] == '/') {
+      skipLineComment(First, End);
+      return;
+    }
+
+    // Cannot be a comment.
+    if (First[1] != '*')
+      return;
+
+    // "/*...*/".
+    skipBlockComment(First, End);
+  }
+}
+
+void Minimizer::printAdjacentModuleNameParts(const char *&First,
+                                             const char *const End) {
+  // Skip over parts of the body.
+  const char *Last = First;
+  do
+    ++Last;
+  while (Last != End && (isIdentifierBody(*Last) || *Last == '.'));
+  append(First, Last);
+  First = Last;
+}
+
+bool Minimizer::printAtImportBody(const char *&First, const char *const End) {
+  for (;;) {
+    skipWhitespace(First, End);
+    if (First == End)
+      return true;
+
+    if (isVerticalWhitespace(*First)) {
+      skipNewline(First, End);
+      continue;
+    }
+
+    // Found a semicolon.
+    if (*First == ';') {
+      put(*First++).put('\n');
+      return false;
+    }
+
+    // Don't handle macro expansions inside @import for now.
+    if (!isIdentifierBody(*First) && *First != '.')
+      return true;
+
+    printAdjacentModuleNameParts(First, End);
+  }
+}
+
+void Minimizer::printDirectiveBody(const char *&First, const char *const End) {
+  skipWhitespace(First, End); // Skip initial whitespace.
+  printToNewline(First, End);
+  while (Out.back() == ' ')
+    Out.pop_back();
+  put('\n');
+}
+
+LLVM_NODISCARD static const char *lexRawIdentifier(const char *First,
+                                                   const char *const End) {
+  assert(isIdentifierBody(*First) && "invalid identifer");
+  const char *Last = First + 1;
+  while (Last != End && isIdentifierBody(*Last))
+    ++Last;
+  return Last;
+}
+
+LLVM_NODISCARD static const char *
+getIdentifierContinuation(const char *First, const char *const End) {
+  if (End - First < 3 || First[0] != '\\' || !isVerticalWhitespace(First[1]))
+    return nullptr;
+
+  ++First;
+  skipNewline(First, End);
+  if (First == End)
+    return nullptr;
+  return isIdentifierBody(First[0]) ? First : nullptr;
+}
+
+Minimizer::IdInfo Minimizer::lexIdentifier(const char *First,
+                                           const char *const End) {
+  const char *Last = lexRawIdentifier(First, End);
+  const char *Next = getIdentifierContinuation(Last, End);
+  if (LLVM_LIKELY(!Next))
+    return IdInfo{Last, StringRef(First, Last - First)};
+
+  // Slow path, where identifiers are split over lines.
+  SmallVector<char, 64> Id(First, Last);
+  while (Next) {
+    Last = lexRawIdentifier(Next, End);
+    Id.append(Next, Last);
+    Next = getIdentifierContinuation(Last, End);
+  }
+  return IdInfo{
+      Last,
+      SplitIds.try_emplace(StringRef(Id.begin(), Id.size()), 0).first->first()};
+}
+
+void Minimizer::printAdjacentMacroArgs(const char *&First,
+                                       const char *const End) {
+  // Skip over parts of the body.
+  const char *Last = First;
+  do
+    ++Last;
+  while (Last != End &&
+         (isIdentifierBody(*Last) || *Last == '.' || *Last == ','));
+  append(First, Last);
+  First = Last;
+}
+
+bool Minimizer::printMacroArgs(const char *&First, const char *const End) {
+  assert(*First == '(');
+  put(*First++);
+  for (;;) {
+    skipWhitespace(First, End);
+    if (First == End)
+      return true;
+
+    if (*First == ')') {
+      put(*First++);
+      return false;
+    }
+
+    // This is intentionally fairly liberal.
+    if (!(isIdentifierBody(*First) || *First == '.' || *First == ','))
+      return true;
+
+    printAdjacentMacroArgs(First, End);
+  }
+}
+
+/// Looks for an identifier starting from Last.
+///
+/// Updates "First" to just past the next identifier, if any.  Returns true iff
+/// the identifier matches "Id".
+bool Minimizer::isNextIdentifier(StringRef Id, const char *&First,
+                                 const char *const End) {
+  skipWhitespace(First, End);
+  if (First == End || !isIdentifierHead(*First))
+    return false;
+
+  IdInfo FoundId = lexIdentifier(First, End);
+  First = FoundId.Last;
+  return FoundId.Name == Id;
+}
+
+bool Minimizer::lexAt(const char *&First, const char *const End) {
+  // Handle "@import".
+  const char *ImportLoc = First++;
+  if (!isNextIdentifier("import", First, End)) {
+    skipLine(First, End);
+    return false;
+  }
+  makeToken(decl_at_import);
+  append("@import ");
+  if (printAtImportBody(First, End))
+    return reportError(
+        ImportLoc, diag::err_dep_source_minimizer_missing_sema_after_at_import);
+  skipWhitespace(First, End);
+  if (First == End)
+    return false;
+  if (!isVerticalWhitespace(*First))
+    return reportError(
+        ImportLoc, diag::err_dep_source_minimizer_unexpected_tokens_at_import);
+  skipNewline(First, End);
+  return false;
+}
+
+bool Minimizer::lexModule(const char *&First, const char *const End) {
+  IdInfo Id = lexIdentifier(First, End);
+  First = Id.Last;
+  bool Export = false;
+  if (Id.Name == "export") {
+    Export = true;
+    skipWhitespace(First, End);
+    if (!isIdentifierBody(*First)) {
+      skipLine(First, End);
+      return false;
+    }
+    Id = lexIdentifier(First, End);
+    First = Id.Last;
+  }
+
+  if (Id.Name != "module" && Id.Name != "import") {
+    skipLine(First, End);
+    return false;
+  }
+
+  skipWhitespace(First, End);
+
+  // Ignore this as a module directive if the next character can't be part of
+  // an import.
+
+  switch (*First) {
+  case ':':
+  case '<':
+  case '"':
+    break;
+  default:
+    if (!isIdentifierBody(*First)) {
+      skipLine(First, End);
+      return false;
+    }
+  }
+
+  if (Export) {
+    makeToken(cxx_export_decl);
+    append("export ");
+  }
+
+  if (Id.Name == "module")
+    makeToken(cxx_module_decl);
+  else
+    makeToken(cxx_import_decl);
+  append(Id.Name);
+  append(" ");
+  printToNewline(First, End);
+  append("\n");
+  return false;
+}
+
+bool Minimizer::lexDefine(const char *&First, const char *const End) {
+  makeToken(pp_define);
+  append("#define ");
+  skipWhitespace(First, End);
+
+  if (!isIdentifierHead(*First))
+    return reportError(First, diag::err_pp_macro_not_identifier);
+
+  IdInfo Id = lexIdentifier(First, End);
+  const char *Last = Id.Last;
+  append(Id.Name);
+  if (Last == End)
+    return false;
+  if (*Last == '(') {
+    size_t Size = Out.size();
+    if (printMacroArgs(Last, End)) {
+      // Be robust to bad macro arguments, since they can show up in disabled
+      // code.
+      Out.resize(Size);
+      append("(/* invalid */\n");
+      skipLine(Last, End);
+      return false;
+    }
+  }
+  skipWhitespace(Last, End);
+  if (Last == End)
+    return false;
+  if (!isVerticalWhitespace(*Last))
+    put(' ');
+  printDirectiveBody(Last, End);
+  First = Last;
+  return false;
+}
+
+bool Minimizer::lexPragma(const char *&First, const char *const End) {
+  // #pragma.
+  skipWhitespace(First, End);
+  if (First == End || !isIdentifierHead(*First))
+    return false;
+
+  IdInfo FoundId = lexIdentifier(First, End);
+  First = FoundId.Last;
+  if (FoundId.Name == "once") {
+    // #pragma once
+    skipLine(First, End);
+    makeToken(pp_pragma_once);
+    append("#pragma once\n");
+    return false;
+  }
+
+  if (FoundId.Name != "clang") {
+    skipLine(First, End);
+    return false;
+  }
+
+  // #pragma clang.
+  if (!isNextIdentifier("module", First, End)) {
+    skipLine(First, End);
+    return false;
+  }
+
+  // #pragma clang module.
+  if (!isNextIdentifier("import", First, End)) {
+    skipLine(First, End);
+    return false;
+  }
+
+  // #pragma clang module import.
+  makeToken(pp_pragma_import);
+  append("#pragma clang module import ");
+  printDirectiveBody(First, End);
+  return false;
+}
+
+bool Minimizer::lexEndif(const char *&First, const char *const End) {
+  // Strip out "#else" if it's empty.
+  if (top() == pp_else)
+    popToken();
+
+  // If "#ifdef" is empty, strip it and skip the "#endif".
+  //
+  // FIXME: Once/if Clang starts disallowing __has_include in macro expansions,
+  // we can skip empty `#if` and `#elif` blocks as well after scanning for a
+  // literal __has_include in the condition.  Even without that rule we could
+  // drop the tokens if we scan for identifiers in the condition and find none.
+  if (top() == pp_ifdef || top() == pp_ifndef) {
+    popToken();
+    skipLine(First, End);
+    return false;
+  }
+
+  return lexDefault(pp_endif, "endif", First, End);
+}
+
+bool Minimizer::lexDefault(TokenKind Kind, StringRef Directive,
+                           const char *&First, const char *const End) {
+  makeToken(Kind);
+  put('#').append(Directive).put(' ');
+  printDirectiveBody(First, End);
+  return false;
+}
+
+static bool isStartOfRelevantLine(char First) {
+  switch (First) {
+  case '#':
+  case '@':
+  case 'i':
+  case 'e':
+  case 'm':
+    return true;
+  }
+  return false;
+}
+
+bool Minimizer::lexPPLine(const char *&First, const char *const End) {
+  assert(First != End);
+
+  skipWhitespace(First, End);
+  assert(First <= End);
+  if (First == End)
+    return false;
+
+  if (!isStartOfRelevantLine(*First)) {
+    skipLine(First, End);
+    assert(First <= End);
+    return false;
+  }
+
+  // Handle "@import".
+  if (*First == '@')
+    return lexAt(First, End);
+
+  if (*First == 'i' || *First == 'e' || *First == 'm')
+    return lexModule(First, End);
+
+  // Handle preprocessing directives.
+  ++First; // Skip over '#'.
+  skipWhitespace(First, End);
+
+  if (First == End)
+    return reportError(First, diag::err_pp_expected_eol);
+
+  if (!isIdentifierHead(*First)) {
+    skipLine(First, End);
+    return false;
+  }
+
+  // Figure out the token.
+  IdInfo Id = lexIdentifier(First, End);
+  First = Id.Last;
+  auto Kind = llvm::StringSwitch<TokenKind>(Id.Name)
+                  .Case("include", pp_include)
+                  .Case("__include_macros", pp___include_macros)
+                  .Case("define", pp_define)
+                  .Case("undef", pp_undef)
+                  .Case("import", pp_import)
+                  .Case("include_next", pp_include_next)
+                  .Case("if", pp_if)
+                  .Case("ifdef", pp_ifdef)
+                  .Case("ifndef", pp_ifndef)
+                  .Case("elif", pp_elif)
+                  .Case("else", pp_else)
+                  .Case("endif", pp_endif)
+                  .Case("pragma", pp_pragma_import)
+                  .Default(pp_none);
+  if (Kind == pp_none) {
+    skipDirective(Id.Name, First, End);
+    return false;
+  }
+
+  if (Kind == pp_endif)
+    return lexEndif(First, End);
+
+  if (Kind == pp_define)
+    return lexDefine(First, End);
+
+  if (Kind == pp_pragma_import)
+    return lexPragma(First, End);
+
+  // Everything else.
+  return lexDefault(Kind, Id.Name, First, End);
+}
+
+static void skipUTF8ByteOrderMark(const char *&First, const char *const End) {
+  if ((End - First) >= 3 && First[0] == '\xef' && First[1] == '\xbb' &&
+      First[2] == '\xbf')
+    First += 3;
+}
+
+bool Minimizer::minimizeImpl(const char *First, const char *const End) {
+  skipUTF8ByteOrderMark(First, End);
+  while (First != End)
+    if (lexPPLine(First, End))
+      return true;
+  return false;
+}
+
+bool Minimizer::minimize() {
+  bool Error = minimizeImpl(Input.begin(), Input.end());
+
+  if (!Error) {
+    // Add a trailing newline and an EOF on success.
+    if (!Out.empty() && Out.back() != '\n')
+      Out.push_back('\n');
+    makeToken(pp_eof);
+  }
+
+  // Null-terminate the output. This way the memory buffer that's passed to
+  // Clang will not have to worry about the terminating '\0'.
+  Out.push_back(0);
+  Out.pop_back();
+  return Error;
+}
+
+bool clang::minimize_source_to_dependency_directives::computeSkippedRanges(
+    ArrayRef<Token> Input, llvm::SmallVectorImpl<SkippedRange> &Range) {
+  struct Directive {
+    enum DirectiveKind {
+      If,  // if/ifdef/ifndef
+      Else // elif,else
+    };
+    int Offset;
+    DirectiveKind Kind;
+  };
+  llvm::SmallVector<Directive, 32> Offsets;
+  for (const Token &T : Input) {
+    switch (T.K) {
+    case pp_if:
+    case pp_ifdef:
+    case pp_ifndef:
+      Offsets.push_back({T.Offset, Directive::If});
+      break;
+
+    case pp_elif:
+    case pp_else: {
+      if (Offsets.empty())
+        return true;
+      int PreviousOffset = Offsets.back().Offset;
+      Range.push_back({PreviousOffset, T.Offset - PreviousOffset});
+      Offsets.push_back({T.Offset, Directive::Else});
+      break;
+    }
+
+    case pp_endif: {
+      if (Offsets.empty())
+        return true;
+      int PreviousOffset = Offsets.back().Offset;
+      Range.push_back({PreviousOffset, T.Offset - PreviousOffset});
+      do {
+        Directive::DirectiveKind Kind = Offsets.pop_back_val().Kind;
+        if (Kind == Directive::If)
+          break;
+      } while (!Offsets.empty());
+      break;
+    }
+    default:
+      break;
+    }
+  }
+  return false;
+}
+
+bool clang::minimizeSourceToDependencyDirectives(
+    StringRef Input, SmallVectorImpl<char> &Output,
+    SmallVectorImpl<Token> &Tokens, DiagnosticsEngine *Diags,
+    SourceLocation InputSourceLoc) {
+  Output.clear();
+  Tokens.clear();
+  return Minimizer(Output, Tokens, Input, Diags, InputSourceLoc).minimize();
+}